The highly folded surface integument of male and female schistosomes has previously hampered study of the transport of radiolabeled metabolic substrates (because isotopic material may passively sequester in this irregular surface). Our pilot studies indicate that the use of simultaneous triple isotope technology (developed in this laboratory) permits estimation of the quantity of unassimilated metabolite and provides a precise quantification of schistosomal metabolite incorporation. Using these techniques, integumental transport of glucose (and other hexoses), amino acids, organic acids, nucleic acid precursors, amines, and certain other non-metabolites will be defined in adult male and female schistosomes. The proposed study will provide information concerning the surface exchange of metabolic substrates between the integuments of male and female schistosomes, and define male-female differences in glucose utilization as well as metabolite uptake. Definition of these parameters will be utilized in the development of an in vitro drug screening model which could conceivably permit rapid determination of antischistosomal activity of many compounds in a relatively short time. The schistosomal integuments are surface sites where physiological exchanges of metabolic substrates occur, and coincidently represent sites of vulnerability to antibodies and blood borne chemicals. Our preliminary studies suggest that certain drugs may restrict incorporation of amino acids, and that there is an antibody which inhibits glucose uptake in schistosomes. We propose to determine whether this serum component is effective in one or more schistosome species, and whether it also inhibits glucose uptake in other parasites, tumor cells, or tissues of the vertebrate host in an attempt to place the significance of our preliminary findings in a perspective relative to potential clinical therapy. If an antibody with specific affinity for the glucose transport site is defined, these studies may provide a foundation for development of an antischistosomal vaccine.